Some VPN providers declined to comment for a news story for fear of drawing China's attention and potential restrictions on VPNs.

At least one Chinese city has adopted a further measure to monitor Internet traffic. The southern city of Guangzhou this month ordered Internet service providers to install "security monitoring" software on all servers and threatened punishment for failure to do so, according to government notices posted on the blog of one data center management company. Two such software programs, called Blue Shield and Huadun, were recommended in one of the government notices. Huadun's Web site says the program helps server owners remove illegal and pornographic content from their systems.

The software is meant to "create a favorable online environment" for China's National Day celebration next week, the government orders said. A representative of the data center company reached by phone said it put the orders on the blog for reference by clients and that the order applied only to Guangzhou.

Some of China's new security measures could remain in place long after the 60th anniversary celebrations, but others are likely to be lifted. China has long gone through cycles of blocking and allowing access to Web sites such as YouTube and Wikipedia, and updates to Freegate have repeatedly allowed the tool to bypass evolving government security measures against it.

Still, Chinese users have posted skeptical notes on Twitter about China's newest Internet controls. When asked if Twitter and Facebook would be unblocked after the National Day celebration next week, one user said they would not.